I have some serious reservations about Senneliers, so I'd certainly agree with him. Schmincke is probably my favorite among the most easily available brands (that is, the ones my local art store carries in open stock). I don't think I've ever had one crumble on me or turn out to be hard and scratchy.
I've never yet gotten my paws on Great Americans. Yours is certainly not the first strong endorsement I've heard for that brand. I admit I was a little taken aback by their color names. I usually expect something like "Deep Umber Tint 3" instead of "Burnt Reynolds"! But it sounds like I should watch for sales on those so I can try them out.
I've seen your posts about the technical hurdles in working so large in pastel. Now that's an area I'm not too courageous with--my largest pastel so far is only 18x24! I'm going to make some oversize sticks like the giant Senneliers. Do you ever use those?
I've talked to Kitty Wallis several times via PM, and she is incredibly helpful and generous with her time. I have a sample kit of her white pastel base she kindly sent me that I have to test and review; the pre-mixed white has some problems with setting up in the jar, and the kit should get around that. In her work she wants very clean, high-chroma, ungreyed colors, and the pigments in her line are all chosen with that goal in mind. The Wallis doughs are the best way I've found for a home pastel maker to deal with pthalos and quinacridones, which are a bear and a half to mix by hand due to how finely powdered they are and their staining potential.
Man, I'm raring to go mix some colors now.
What I really enjoy doing, and have done several times now, is to make a dozen or so custom sticks for each commission as a way of building up my collection, and I've got five new commissions lined up. I hope my new pigments get here soon.